This invention relates to packaging apparatus for packaging small products into a multi-pocket blister pack. This kind of apparatus is commonly used for packaging pharmaceutical products, such as capsules and tablets. Such products may take a variety of different shapes and sizes, and may be made out of a variety of different materials with different properties of strength, hardness and, particularly in the case of soft gelatine capsules, tackiness.
Packaging machines of this kind typically include four stations on a track along which a continuous web, made for example of PVC (polyvinylchloride), passes. The first station is typically a pocket-forming station at which a two-dimensional matrix of pockets are either thermo-formed, to produce pockets of a more or less exact product shape with well defined edges, or cold-formed, to produce broad and shallow concave pockets substantially larger in area than the individual items of product. The second station is a feeding station, at which a plurality of chutes deliver product to the pockets across the web. At the third station, a top closure foil is applied across the top of the web, sealing the product into the pockets. At the fourth and final station, individual blister packs are punched out of the continuous web.
This invention is particularly concerned with feeding apparatus which may be located at the feeding station.
There are two general types of machine known in the art. In a continuous motion machine, the web moves continuously under dedicated vertical feed chutes at the feeding station to allow product to fall freely into the matrix of pockets as the web travels under the outlets of the chutes. In an intermittent motion machine, indexed movements of the web past the feeding station allow it to be fed while stationary from chutes in which, typically, pairs of sliding gates meter a single product at a time into each pocket.
In each case the feed chutes are fed from a hopper which is vibrated to allow product to drop into the tops of the respective chutes.
Intermittent feed machines generally operate at about 45-60 cycles per minute. Continuous motion machines are rated according to the speed of the web, which typically travels at from 10-14 meters per minute. A continuous motion machine can give faster output, especially for smaller packs, but gives problems with some products, such as soft capsules, and with the wider cold-formed pockets where the flat portions of the web between the pockets cannot precisely cut off the supply of single products as the pockets pass under the delivery chutes. Continuous motion also tends to give a greater reject rate, as the product is more likely to be chipped or sheared if it is not delivered cleanly into each pocket. The efficiency of a continuous motion machine may be 98.5%, as against 99.5% or better for an intermittent motion machine.
This invention is concerned with improving the efficiency of feeding apparatus for a continuous motion packaging line. Product feeding apparatus for delivering items of product into pockets in a continuously travelling web comprises a plurality of product delivery chutes positioned over the paths of the products in the web. According to the invention, the product delivery chutes are mounted on a carriage that reciprocates along the direction of travel of the web in a cycle that includes a stage in which the carriage synchronises its speed with the speed of the web and releases the items of product while the delivery chutes are positioned over corresponding pockets in the travelling web.
Other preferred features of the invention will be apparent from the following description and appended claims.